1. Field of the Invention
The present invention relates to a buckle device for seatbelt systems of motor vehicles and so forth.
2. Description of the Related Art
In a buckle device, it is desirable that frictional force in the insertion/withdrawal path of the tongue plate be limited as far as possible during the period following the insertion of the tongue plate until a lock plate securely engages therewith. In one arrangement devised to meet the above-mentioned requirement, failure to fully insert the tongue plate into the place where it securely engages with the lock plate causes a spring-loaded ejector to push the tongue plate back out of the buckle device, whereby it is assured that tongue plate insertion and tongue plate's firm engagement with the lock plate are promoted.
However, it is noted that the lock plate is at all times urged in a direction towards the path of tongue plate insertion so that the lock plate may be readily and immediately engaged with the tongue plate when the tongue plate is inserted and reaches the engagement position. Due to the urging of the lock plate towards the tongue plate the tongue plate confronts a pushing force from the lock plate while the tongue plate is being inserted into the engagement position, with some frictional resistance being generated thereby. In some cases, to lessen the frictional resistance, certain measures are taken wherein the faces of the lock and tongue plates are processed so as to be smooth, and a large ejector spring is applied to provide the ejector with larger spring force, requiring greater force for tongue plate insertion.